1. Field of the Disclosure
In one aspect, this disclosure generally relates to methods and apparatuses for characterizing a parameter of interest of an earth formation using gravitational measurements. In another aspect this disclosure generally relates to methods and apparatuses for estimating differences in frames of reference for gravitational measurements.
2. Background of the Art
In many fields of endeavor, it may be useful to characterize a parameter relating to an earth formation, such as parameters relating to one or more fluids of the earth formation. For example, in exploration, development, and monitoring related to hydrocarbon production, it is important to make accurate measurements of geologic formations. The geologic formations below the surface of the earth may contain reservoirs of oil and gas or underground bodies of water. The geologic formations may include formation layers and various structures. In a quest for oil and gas, it is important to know about the location and composition of the formation layers and the various structures. In particular, it is important to know about the geologic formations with a high degree of accuracy so that resources are not wasted. The present disclosure addresses the need to obtain information relating to geologic formations over the life of a reservoir.
One way of characterizing an earth formation is by using gravity measurements to estimate hydrocarbon or other fluid movement. Time-lapse reservoir monitoring is an important application for borehole gravimeters. Hydrocarbons in earth formations, such as reservoirs, are subject to the migration of fluids (oil, water, gas, etc.) over time. Detecting, measuring, and mapping the movement of these fluids may be useful for estimating the producible hydrocarbon content of an earth formation and improving hydrocarbon recovery. The hydrocarbon movement may also be used to estimate the rate of depletion of a reservoir.